But the geological and geochemical analyses showed that there existed a set of high quality marine source rock in the platform slope facies of Middle Ordovician Pingliang Formation.

• 地质和地球化学分析证实，盆地西、南缘台缘深水斜坡相的中奥陶统平凉组存在优质海相烃源岩，其形成的油气最早富集在中央古隆起及其周围；